Navigation apparatuses, methods, and programs for generation of a 3D movie

ABSTRACT

Navigation apparatuses, methods, and programs set a reference point on a route, set at least one point on the route on the basis of the reference point, and set a region along the route, the region being set on the basis of the set at least one point and the region including the at least one point. The navigation apparatuses, methods, and programs obtain 3D map data corresponding to the region, generate a 3D movie which has a predetermined viewpoint on the basis of the obtained 3D map data, and display the generated 3D movie.

INCORPORATION BY REFERENCE

The disclosure of Japanese Patent Application No. 2006-182794, filed onJun. 30, 2006, including the specification, drawings and abstractthereof, is incorporated herein by reference in its entirety.

BACKGROUND

1. Related Technical Fields

Related technical fields include navigation apparatuses, and moreparticularly, a navigation apparatuses providing a moving 3D image on aroute guidance screen.

2. Description of the Related Art

In recent years, navigation apparatuses for aiding in the navigation ofvehicles have become very popular. Such a navigation apparatus searchesfor a route from a starting point to a destination, detects a currentposition of a vehicle by means of a GPS (Global Positioning System)and/or a gyro, and displays the route to the destination and the currentposition of the vehicle. It is important for such a navigation apparatusto provide an understandable display to a driver of the vehicle. Forexample, a navigation apparatus for a vehicle disclosed in JapaneseUnexamined Patent Application Publication No. 10-115529 provides a 3D(3D) movie which is presented from the viewpoint of a driver.

The navigation apparatus disclosed in Japanese Unexamined PatentApplication Publication No. 10-115529 provides guidance regarding anintersection by drawing a route on a 3D map in which structures, such asbuildings, are displayed. When a two-dimensional map is used, the driverneeds to figure out how the two-dimensional map corresponds to the realview. However, the navigation apparatus with the structure disclosed inJapanese Unexamined Patent Application Publication No. 10-115529displays a 3D movie, so that it is easier for the driver to compare themap with the real view.

As shown in FIG. 12, to generate the 3D movie, the navigation apparatusmeasures off 3D map data 102 in rectangular regions (each rectangularregion is denoted by reference numeral 100 and all of the rectangularregions include a route 101). The navigation apparatus selects one ofthe rectangular regions 100 corresponding to the current position of thevehicle, reads data of the rectangular region 100 stored in a memory,and generates the 3D movie on the basis of the read data.

SUMMARY

However, the volume of the 3D map data is so large that a considerableamount of the memory of the navigation apparatus is required to storethe data when the navigation apparatus reads the 3D map data on aregion-by-region basis. The amount of memory installed in the navigationapparatus is limited. However, the navigation apparatus mounted in thevehicle is required to provide a movie that is updated in real timealong with the motion of the vehicle.

Accordingly, various exemplary implementations of the broad principlesdescribed herein provide a navigation apparatus for providing routeguidance by means of a 3D movie while requiring use of a smaller amountof memory.

Various exemplary implementations provide navigation apparatuses,methods, and programs that may set a reference point on a route, may setat least one point on the route on the basis of the reference point, andmay set a region along the route, the region being set on the basis ofthe set at least one point and the region including the at least onepoint. The navigation apparatuses, methods, and programs may obtain 3Dmap data corresponding to the region, may generate a 3D movie which hasa predetermined viewpoint on the basis of the obtained 3D map data, andmay display the generated 3D movie.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary implementations will now be described with reference to theaccompanying drawings, wherein:

FIG. 1 is a diagram illustrating an exemplary data management method;

FIG. 2 is a diagram illustrating an exemplary navigation apparatus;

FIG. 3 is a diagram illustrating an exemplary road guidance system;

FIG. 4 is a diagram illustrating an exemplary guidance screen in thenavigation apparatus;

FIG. 5 is a diagram illustrating an exemplary coordinate system;

FIG. 6 is a diagram illustrating an exemplary method of setting drawinga reference point;

FIGS. 7A-7C are diagrams illustrating an exemplary method for setting aregion for which data is to be read;

FIG. 8 is a diagram illustrating an example of regions for which data isto be read;

FIG. 9 is a diagram illustrating an exemplary method of determiningstructures within the region for which data is to be read;

FIG. 10 is a flowchart illustrating an exemplary method of providingroute guidance;

FIG. 11 is a flowchart illustrating an exemplary method of providingroute guidance; and

FIG. 12 is a diagram showing a conventional navigation apparatus/method.

DETAILED DESCRIPTION OF EXEMPLARY IMPLEMENTATIONS

FIG. 1 shows an exemplary method for managing route data. As shown inFIG. 1, rectangular regions 22 a through 22 d along a route 2 for whichdata is to be read may be set in accordance with the shape of route 2.Each of the rectangular regions may be set as having a centerline, whichpasses through two points set on the route 2. The navigation apparatus 1may read 3D map data 22 included in the regions 22 a through 22 d andmay draw the map, so that it may be possible for the navigationapparatus 1 to draw the 3D movie. In this case, the memory usage may bereduced compared to the known way of setting rectangular regions forwhich data is to be read.

FIG. 2 is a diagram illustrating an example of hardware configuration ofnavigation apparatus. Navigation apparatus 1 may include a controller(e.g., CPU 5), a ROM 6, a RAM 7, a communication control section 8, astorage section 9, GPS section 10, a vehicle speed sensor 12, gyro 13,an image display section 14, and so forth, and these sections may beconnected, and may provide route guidance to a set destination.

The CPU 5 may be a central processing device, and may perform variousinformation processing such as route search, route guidance, and soforth. The CPU 5 may control the navigation apparatus 1 based onprograms stored in ROM 6, RAM 7, a storage section 9, and so forth. TheROM 6 may be a read-only memory and may store basic programs, parametersand so forth for operating the navigation apparatus 1. The RAM 7 may bea random access memory enabling writing in/reading out. For example, itmay provide a working memory for CPU 5 to perform various informationprocessing. Map data for display may be read in to the RAM 7 from thestorage section 9. The communication control section 8 may be afunctional section for connecting to a network such as Internet. TheNavigation apparatus 1 may communicate with an external server throughthe communication control section 8.

The storage section 9 may be a storage device with mass-storage mediumsuch as a semiconductor memory, a hard disk, an optical disk, a magnetooptical disk and so forth, and may form a program storage section 17 anda data storage section 18. The program storage section 17 may store anOS (Operating System), i.e., a basic program for operating thenavigation apparatus 1, a route guidance program for CPU 5 to perform aroute guidance processing, and so forth.

The data storage section 18 may store map data made up oftwo-dimensional road data 20, two-dimensional road detail data 21, 3Dmap data 22, and so forth. Two-dimensional road data 20 may be map datadisplaying a road network with links that are connecting nodes.Two-dimensional road data 20 may be used, for example, for CPU 5 tosearch for a route from a departing point to a destination.

The two-dimensional road detail data 21 may be the map data for CPU 5 todisplay a two-dimensional map on an image display section 14. Thetwo-dimensional road detail data 21 may include information of roadtraffic lanes or information relating to various facilities such asrestaurants, gas stations, schools, factories, and so forth.Accordingly, it may be possible to provide detailed geographicinformation to the driver. The 3D map data 22 may be 3D city map datadisplaying a city with 3D computer graphics using 3D map data thatdefines 3D information on structures. The term “structure” here refersto all displayed elements such as, for example, roads, railroads,buildings, ground and so forth, and each structure may be given anattribute indicating an element classification of the structure such as“road,” “railroad,” “building,” and/or “ground.”

The GPS section 10 may receive GPS signal sent by an orbiting GPSsatellite and provide it to CPU 5. The vehicle speed sensor 12 may be asensor for detecting the speed of vehicle. The Gyro 13 may be a sensorfor detecting the angular velocity of vehicle.

With the GPS signal, the vehicle speed, the angular velocity and/or soforth, the CPU 5 may calculate the driving condition of vehicle such aslatitude and longitude of the current location, the traveling direction,the speed, the acceleration, and/or so forth.

The image display section 14 may include, for example, an LCD, plasmadisplay, or other display devices, and may display the guidance screenthat CPU 5 creates with two-dimensional road detail data 21, 3D map data22, and so forth. The image display section 14 may also have a touchpanel function so that the driver may set a destination or otherinformation in the navigation apparatus 1 by touching a menu shown onthe display monitor. Thus, the image display section 14 may function asdestination set receiving means for receiving a setting of adestination. Note that, although not shown, the navigation apparatus 1may include an audio output function so that it may provide routeguidance with audio beside with the guidance screen.

FIG. 3 is a diagram illustrating an example of the system configurationof a road guidance system. The road guidance system 29 may be formedwhen CPU 5 performs the route guidance program stored in the programstorage section 17. The current location data generating section 25 maygenerate current location data of a vehicle on the basis of the GPSsignal from GPS section 10, detected speed from the vehicle speed sensor12, the gyro 13 and so forth. The current location data may includeinformation presenting the driving condition of vehicle such as latitudeand longitude of the current location, the traveling direction, thespeed, the acceleration, and/or so forth.

The map data extracting section 26 may receive the current location datafrom the current location data generating section 25 and may extractsmap data from two-dimensional road detail data 21 and 3D map data 22 toprovide guidance at the current location. As described later, regarding3D map data 22, the map data extracting section 26 may set a region forwhich data is to be read along the route and may extract structureslocated within the region for which data is to be read, from among thestructures in 3D map data 22.

The map image data output section 27 may generate map image data forguidance with two-dimensional road detail data and 3D map data extractedby the map data extracting section 26 and may output the image on theimage display section 14. The map image data output section 27 mayobtain current location data from the current location data generatingsection 25 and may display the current driving location of the vehicle,the traveling direction, and so forth with a moving two-dimensionalimage and/or a moving 3D image on the basis of this data.

Regarding the moving 3D image, the map image data output section 27 mayset a viewpoint on the basis of the current location acquired by thecurrent location data generating section 25, and may calculate thetwo-dimensional image data which is for drawing the scene from thisviewpoint in perspective by means of 3D map data. Then the map imagedata output section 27 may create two-dimensional image data in realtime in accordance with the motion of the viewpoint. By displaying theseries of the created data sequentially on the image display section 14,a moving 3D image may be displayed on the image display section 14.Thus, the map image data output section 27 may function as a moving 3Dimage generator for generating a moving 3D image viewed frompredetermined viewpoint on the basis of 3D map data 22.

Note that the terms “movie,” “moving image,” and “motion-image”described herein contemplate a picture shifts smoothly or still imageswhich are displayed at predetermined intervals so that driver mayrecognize their consecutive relation. When displaying moving images, thesmoother the movie displayed, the more processing ability or memory ofCPU 5 is consumed. Therefore, presenting a moving image by usingconsecutive still images may decrease the load of the navigationapparatus 1. Each still images consecutively displayed may be a stillimage in which the viewpoint moves in accordance with the movement ofcurrent location. A relative position of viewpoint with respect to thetraveling vehicle may be identical; however, the relative position maychange in accordance with the movement of current location.

FIG. 4 is a diagram illustrating an example of a guidance screendisplayed on the image display section 14. The guidance screen 30 mayinclude a two-dimensional map screen 31 and a 3D map screen 33. Thetwo-dimensional map screen 31 may be drawn with two-dimensional roaddetail data 21, and the 3D map screen 33 is drawn with 3D map data 22.Note that the guidance screen may have various display modes. Therefore,it may be possible to display a two-dimensional map screen 31 on a fullscreen or the enlarged two-dimensional map at the position of the 3D mapscreen 33.

On the two-dimensional map screen 31, the current location and thetraveling direction of vehicle may be displayed as self-vehicle icon 32on the two-dimensional map. On the 3D map screen 33, the moviepresenting a visible scene from a vehicle perspective may be displayedby 3D computer graphics. The direction and/or location of viewpoint maybe adjustable. For example, it may generally face the travelingdirection of the vehicle. In addition, the viewpoint may be set abovevehicle, and current position and traveling direction of vehicle may bedisplayed as self-vehicle icon 36.

On the 3D map screen 33, a route 37 and/or traffic lane information 38may be displayed. By following 3D map screen 33, a driver may change acourse or change a lane. In addition, on the 3D map screen 33, adistance indicator 39 may be displayed indicating the remaining distanceto the guidance intersection that gives guidance of a course change. Themaximum distance to guidance intersection (300 m in FIG.) and theremaining distance to guidance intersection (corresponding to the lengthof the bar) may be displayed. Additionally, at the top of the 3D mapscreen 33, the name of the intersection 34 and an arrow 35 representinga turning direction may be displayed.

The navigation apparatus 1 may normally display the two-dimensional mapscreen 31 on the full guidance screen 30. When vehicle approaches aguidance intersection, it may begin to display the 3D map screen 33. The3D map screen 33 may keep being displayed until the vehicle passesthrough the guidance intersection. This moving 3D image for routeguidance may be called a cut-in movie.

Cut-in movie is one kind of enlarged images of intersection, and drivermay arrange it to be displayed or not displayed. The cut-in movie maydisplayed while vehicle drives on general roads, and the conventionalguidance with the two-dimensional map screen 31 may be provided whendriving on expressways. The resolution of cut-in movie on the screen maybe, for example, 512×480 dots (width×height) on VGA (Video GraphicsArray).

With reference to FIGS. 5-9, an example of generating cut-in movie innavigation apparatus will be explained. This function may be performedby the map data extracting section 26.

FIG. 5 is a diagram illustrating a coordinate system that may be used inthe navigation apparatus 1. The navigation apparatus 1 may sets adrawing reference point 42 as origin of coordinate and sets a longitudedirection along an X-axis in a positive and easterly direction. It mayalso set a latitude direction along a Z-axis in a negative and northerlydirection and a height direction along a Y-axis in a positive and upwarddirection. The drawing reference point 42 is a reference point for themap data extracting section 26 to set a region for which data is to beread, and it may be a specified point on the route. Thus, the navigationapparatus 1 may set a reference point at a specified point on route.

In particular, a point within an intersection on the route may be set asthe specified point (drawing reference point). More specifically, acenter point in an intersection, an intersection node, a closestcomplement point to an intersection node or a center point ofintersection (in case of 3D network data), a center point of a regionwhere an entrance lane to an intersection and a departing lane from anintersection are crossing, and/or so forth. Further, when a specifiedpoint is set at any point but intersections on the route, for example,on a curve, a specified point (a drawing reference point) may be set ata center point of the curve, at a point with largest curvature, on acommon node for two adjacent links on a curve which angle between thetwo links is the smallest, and so forth.

A method of setting a drawing reference point will be described withreference to FIG. 6. The navigation apparatus 1 may sets a drawingreference point in an intersection guidance area 44 of a guidanceintersection. The guidance intersection described here is anintersection where guidance is given by cut-in movie, such as anintersection where guidance route makes a right or left turn, acomplicated intersection such as three-road intersection or five-roadintersection, and/or so forth. Guidance intersections may be determinedalong a route based on their qualities. For example, a condition that anintersection making turns or the like may be preset so that navigationapparatus 1 may detect the intersections fulfilling the search conditionfor guidance intersection. Alternatively, it may be possible to specifyan attribute for each intersection to determine whether guidance shouldbe given or not.

Generally, the navigation apparatus 1 sets a route on links 43 and setsa drawing reference point 47 on a node. A drawing reference point 47 mayalso be determined, for example, at a point other than a node, such asby setting a center point of an intersection guidance area 44 as thedrawing reference point 47. When adjusting a view position in accordancewith turns at a guidance intersection in order to provide bettervisibility of a route in a cut-in movie, the navigation apparatus 1 mayuse the drawing reference point 47 as a viewpoint adjusting referencepoint.

Note that a route may occasionally be determined by means of moredetailed road map data (called 3D network data) such as traffic lanedata, and so forth. When a route is assigned on a node, it is set on thecenter of road, however, when using detail road map data, a route may beset on a specific traffic lane instead of the node. Detail road map datamay provide complement points for drawing a leading curving line duringthe turn. In the case of assigning a route with these detail road mapdata, navigation apparatus 1 may determine a closest complement point toa node to serve as a drawing reference point. Further, navigationapparatus 1 may set a viewpoint adjusting reference point at a pointwhere a route enters an intersection guidance area 44. An arrangementmay also possible to display a guidance line on the left side of road bydisplaying a route on the left of the centerline of the road.

In the example of FIG. 6, one or more drawing reference points 46 may beset at complement points on the route 45. Note that in this diagram, adrawing reference point 46 is shown for two possible routes 45, onehaving a right-tum and one having a left-turn. The point where the route45 enters the intersection guidance area 44 may be set as a viewpointadjusting reference point 48. Note that, when a distance from a pointentering intersection guidance area 44 to a drawing reference point 46is greater than a predetermined distance (e.g., greater than 40 m), anarrangement may be made to set a point which is the intersectionguidance area 44 and a predetermined distance away from a drawingreference point 46 as a viewpoint adjusting reference point.

Next, a method of setting a region for which data is to be read will bedescribed with reference to FIGS. 7A-7C. First, as shown in FIG. 7A,navigation apparatus 1 may set a first point 52 and a second point 53before a drawing reference point 50 (also serving as an origin ofcoordinate) in front of a self-vehicle 51 on the route displayed withdotted line. The first point 52 may be a first distance (herein 80 m)away from a drawing reference point 50 along the route, and the secondpoint 53 may be a point that is a second distance (herein 150 m) awayfrom a drawing reference point 50 along route. The second distance isgreater than the first distance. Note that first distance and seconddistance are set as the distance along route here; however, they may bealternatively set as straight line distance from the drawing referencepoint 50.

Alternatively, a first point and a second point can be respectivelydetermined at a node located in a vicinity of the first distance and anode located in a vicinity of the second distance (e.g., a node which isshortest distance, or a note which is shortest distance from the firstdistance and the second distance in opposite direction from a drawingreference point) by means of two-dimensional road data 20. In this case,a node located about 80 m away from a drawing reference point 50 may beset as a first point, and a node located about 150 m away from a drawingreference point 50 may be set as a second point. If the route is curvedat a node, a node which is adjacent the first point may be the secondpoint.

As described below, navigation apparatus 1 may set a region for whichdata is to be read based on a straight line connecting a first point anda second point along the route. Therefore, navigation apparatus 1 mayset a region for which data is to be read along route that is likely tobe in the driver's field of view. Therefore, setting a region for whichdata is to be read in accordance with the shape of the route (e.g.,points on the route) may reduce or avoid the reading of 3D map data of aregion that is outside the driver's field of view, and thus unnecessary.

As another alternative, for example, a first point may be set and theregion for which data is to be read based on a line that passes throughthe first point and is alongside the link. Thus, navigation apparatus 1includes point setting means for setting at least one point on theroute.

Next, as shown in FIG. 7B, the navigation apparatus 1 may set a line 54having end-points that are the first point 52 and the second point 53.Then, navigation apparatus 1 may extend the side of first point 52 online 54 up to a predetermined length (herein 10 m).

Next, as shown in FIG. 7C, navigation apparatus 1 may form a quadrangle55 having the extended line 54 as a centerline and having apredetermined width (herein 30 m) on each left and right side from thecenterline 54. This quadrangle 55 may be sets as a region for which datais to be read.

Returning to FIG. 7B, extending the centerline 54 predetermined lengthin traveling direction of vehicle is useful to avoid any missing partsin 3D map data to read in, by overlapping a region for which data is tobe read that will be formed ahead of this region for which data is to beread (not shown) with the region for which data is to be read 55. Bysetting a region for which data is to be read as described, 3D map datamay be extracted along route without any missing parts.

Thus, navigation apparatus 1 may set a region along the route based onpoints (first point and second point) as specified above. This regionmay be set as a rectangle (herein oblong) formed with this first andsecond point, and the straight centerline passing through this first andsecond point. Further, the edge of the rectangle at the side of thefirst point (furthest in traveling direction of the vehicle) may beextended a predetermined distance away from the first point by extendingthe centerline in the traveling direction of vehicle.

FIG. 8 is a diagram of an exemplary region for which data is to be readthat navigation apparatus 1 may sets for a guidance intersection. Inorder to obtain as similar shape of a region for which data is to beread as the shape of route possible, the navigation apparatus 1 may seta total of four regions for which data is to be read including regions61, 65, 68, in addition to 55, described above.

In order to set the region 61 for which data is to be read, navigationapparatus 1 may set a first point 62 at 10 m short of a drawingreference point 50 along route and may use point 52 as a second point.The navigation apparatus 1 may form a rectangle that has 30 m on eachleft/right side, and may sets this rectangle as the region 61 for whichdata is to be read. The edge of the region 61 may be located at 30 mextended point of centerline from the first point 62 in the travelingdirection.

The reason for increasing the extension of centerline of the region 61more than the region 55 is that the edge of the region 61 in thetraveling direction is located nearby a guidance intersection. Becausethe traveling direction of vehicle will likely shift in a guidanceintersection, the increased overlaps of region 61 with regions 65 and 67can prevent any interruption or lack of 3D map data in a guidanceintersection in the cut-in movie. That is to say, in order to read in 3Dmap data of the area displayed on a guidance screen even in a guidanceintersection with significant level of turn, an arrangement is made toset a region for which data is to be read relatively large.

The region 65 may be a rectangular region based on a centerline whichpasses through the drawing reference point 50 serving as a first pointand the point 62 serving as a second point, and which has 30 m on eachleft/right side. The centerline may be extended 150 m from the drawingreference point 50. Because when entering an intersection, the scenedirectly ahead of the vehicle will be in good view, navigation apparatus1 sets a relatively large region for which data is to be read in adirection extending in the viewing direction. Thus, when a first pointis located in an intersection, the navigation apparatus 1 may setgreater predetermined distance (length of extension) to extend the edgeof the region on the side of a first point, than other regions.

Regarding region 68, the navigation apparatus 1 may set the drawingreference point 50 as a first point, set a point 67, which is 50 m awayfrom the drawing reference point 50 along the route as a second point,and set a rectangular region with a centerline passing through a firstpoint and a second point as the region 68. The left/right width from acenterline may be 30 m each. The navigation apparatus 1 may quits cut-inmovie after a vehicle completes a turn at a guidance intersection.Therefore, it may not be necessary to extend the center line of theregion 68, which is for drawing a scene after turning. Thus, withoutunnecessary extension of centerline of the region 68, the amount 3D mapdata that must be read is decreased, and consequently the amount ofmemory consumption may be reduced.

Next, a method of determining structure within a region for which datais to be read will be described with reference to FIG. 9. The structuresthat are determined to be located within a region for which data is tobe read may be extracted from 3D data 22. Navigation apparatus 1 (e.g.,via map data extracting section 26) may forms a rectangle (e.g., 72, 73,74) with vertexes of a smallest and a biggest X coordinate and Zcoordinate of the structure on the X-Z plane. If at least a part of thisrectangle is located within a region for which data is to be read (e.g.,region 71), navigation apparatus 1 determines the structure is locatedwithin the region for which data is to be read. If the region of therectangle is not at all located within the region for which data is tobe read, it may be determined that the structure is not located withinthe region for which data is to be read.

According to the specific example shown in FIG. 9, a rectangle 72 isentirely located within a region 71 for which data is to be read. Also,a rectangle 73 is partially located within region 71. Therefore, thestructures corresponding to rectangles 72 and 73 may become a subjectfor extraction. On the other hand, a rectangle 74 is not at all locatedwithin region 71 at all. Therefore, the structure(s) corresponding tothe rectangle 74 may not become a subject for extraction. The navigationapparatus 1 may thus determine whether structures which may be displayedwith 3D map data are located within a region for which data is to beread, and if they are located in a region for which for which data is tobe read, the 3D map data may be read out.

In addition to the above described methods, other conditions may be usedto reduce the amount of memory consumption by further eliminating 3D mapdata to be read. For example, regarding structures whose elementclassification is other than road, it may be possible to avoid reading3D data for small structures, which may not be important for recognizingan area. For example, structures that fit within a sphere havingdiameter of a predetermined length (100 m, for example) and at least apart of the sphere is located within the region for which data is to beread, the structures fitting within the sphere may not be read. Thus,the amount of memory consumption may be decreased. “Elementclassification” here refers to a classification of structure such asroad, railroad, building, and so forth, and it may be associated withgiven to structures as an attribute. Thus, it may also be possible toreduce the 3D data read for the cut-in movie by not reading data forstructures having one or more specified element classifications.

Next, with reference to a flowchart in FIG. 10, an exemplary roadguidance method will be described. The method may be implemented, forexample, by CPU 5 executing a road guidance program.

As shown in FIG. 10, first, navigation apparatus 1 receives adestination setting, e.g., input by a driver (Step 5). Next, thenavigation apparatus 1 performs a route search to the destination bymeans of two-dimensional road data 20 (Step 10), and starts providingguidance on a guidance screen (Step 15).

Then, navigation apparatus 1 sets a drawing reference point on, forexample, a node in a guidance intersection on the route. All the drawingreference points over the entire route may be set in advance, or apredetermined number of drawing reference points which are closest to acurrent location may be set and other drawing reference points may beset sequentially in accordance with the modem of the vehicle.

Next, the navigation apparatus 1 searches for a closest drawingreference point from current location (Step 20), and determines whetherthis drawing reference point is 300 m or more away from the currentlocation (Step 25), e.g., to ensure there is enough time for generatingand displaying a cut-in movie. The distance may be longer or shorterthan 300 m, according to, for example, the information processingcapability of the navigation apparatus 1 and the speed of vehicle.

In the case that the distance from current location to a drawingreference point is less than 300 m (Step 25=No), the navigationapparatus 1 terminates drawing processing of cut-in movie relating tothis drawing reference point (Step 55). In this case, navigationapparatus 1 may display a two-dimensional enlarged image of guidanceintersection instead of cut-in movie.

If the distance from current location to a drawing reference point ismore than 300 m (Step 25=Yes), the navigation apparatus 1 defines aregion for which data is to be read based on this drawing referencepoint (Step 30). Navigation apparatus 1 then reads in the structures inthe region for which data is to be read (set in Step 30) among all thestructures in 3D map data (Step 35).

Next, when the current location of vehicle reaches a point of 300 m awayfrom a drawing reference point, the navigation apparatus 1 generates astill image as part of the 3D movie of the viewpoint located 150 mbefore a drawing reference point, and displays it as a cut-in movie(Step 40). This is still image may notify a driver that a cut-in moviewill be displayed, and in a mean time, for performing a process ofdisplaying 3D movie while the sill picture is displayed. Then whencurrent location of vehicle reaches the point of 150 m away from adrawing reference point, navigation apparatus 1 switches the still imageto the movie, and displays a moving 3D image in real time (Step 45).

Next, navigation apparatus 1 judges whether current location has passeda drawing reference point (Step 50), and in the case of not havingpassed through (Step 50=No), it continues drawing cut-in movie. Whenhaving passed the drawing reference point (Step 50=Yes), navigationapparatus 1 may terminate drawing cut-in movie (Step 55). However, forexample, the cut-in movie may also be terminated when the vehicle goesoff the route or when the vehicle has traveled predetermined distancebeyond the drawing reference point along the route.

Then, navigation apparatus 1 judges whether current location has reacheda destination (Step 60). If the destination is not reached (Step 60=No),operation of the method returns to Step 20 and performs a drawingprocessing of cut-in movie for next drawing reference point. If thecurrent location has reached the destination (Step 60=Yes), navigationapparatus 1 terminates road guidance. Thus, in the present example 1, bysetting region for which data is to be read limitedly along the route,the amount of 3D map data read in for example, RAM 7 (FIG. 2) may bereduced, and consequently, this may decrease the memory consumption.

In the examples above, the navigation apparatus 1 may sequentially setregions for which data is to be read in accordance with the traveling ofvehicle. However, the regions for which data is to be read throughoutthe route may be set and stored at the start of driving, and read themout in accordance with traveling. Because regions for which data is tobe read are set beforehand, when guidance starts, more of the resourcesof CPU 5 may be dedicated displaying cut-in movies during traveling. Aprocedure of this case will be described with reference to a flowchartin FIG. 11. Note that the same processing as FIG. 10 will be given withthe same reference numeral, and the description will be simplified.

As shown in FIG. 1, first, navigation apparatus 1 receives a destinationsetting, e.g., input by a driver (Step 5), and performs a route searchfor destination (Step 10). Next, navigation apparatus 1 sets all thedrawing reference points throughout the route (Step 100). Then,navigation apparatus 1 sets the region for which data is to be read foreach preset drawing reference point, and stores them in a memory such asRAM 7 (FIG.2) or the like (Step 105). Then, navigation apparatus 1starts providing guidance on the guidance screen (Step 15).

Next, navigation apparatus 1 determines whether the next drawingreference point (the first reference point if immediate after thedeparture) is more than 300 m away from current location (Step 26). Inthe event that the distance to next drawing reference point is less than300 m (Step 26=No), navigation apparatus 1 terminates the drawingprocess of cut-in movie for this drawing reference point (Step 55). Inthe event that the distance to next drawing reference point is more than300 m (Step 26=Yes), navigation apparatus 1 reads out the region forwhich data is to be read corresponding to this drawing reference pointstored in memory, and reads in the 3D map data in this region for whichdata is to be read among the 3D map data 22 (Step 110). The rest of theprocess may be the same as the process in the flowchart in FIG. 10.

A guidance procedure with cut-in movie has been described above, but itis possible to give more detailed conditions for display of cut-inmovie. For example, in the case that the distance to an adjacentguidance intersection is more than 150 m and less than 300 m, anarrangement may be made for navigation apparatus 1 to display theguidance image of the next guidance intersection immediately afterpassing the first guidance intersection. In this case, when navigationapparatus 1 successfully draws the cut-in movie at the firstintersection, it may provide guidance with two-dimensional enlargedimage at the next guidance intersection. When it does not draw cut-inmovie at the first guidance intersection, it provides guidance withcut-in movie at the next guidance intersection.

If the distance to an adjacent guidance intersections is less than 150m, the navigation apparatus 1 may provides guidance with atwo-dimensional enlarged image at the next intersection, despite thefact that the guidance provided at the first guidance intersection waswith cut-in movie or two-dimensional enlarged image. Additionally, atrotaries (also called roundabout intersections) or side roads, thenavigation apparatus 1 may provide guidance in the same way as aconventional navigation apparatus.

Various conditions for drawing cut-in movie have been explained above.However, these are for providing as much guidance with cut-in movie aspossible within the limits of an information processing capability ofnavigation apparatus 1. In case that information processing capabilityof navigation apparatus 1 is sufficient, guidance with cut-in movie maybe performed at every guidance intersection, despite of the distancebetween current location and drawing reference point.

Hereinafter, advantages that may be obtained according to one or more ofthe above described examples will be described.

The above described setting of a region for which data is to be readalong the route may decrease the amount of the 3D map data to read inthe memory. The above described setting of a region for which data is tobe read along the route may make it is possible to determine whether anystructure is located within a region for which data is to be read and toprevent reading in unnecessary structure.

According to one or more of the above examples, it is possible todetermine whether to draw a cut-in movie on the basis of the distancebetween current location and drawing reference point, so that the cut-inmovie may be drawn within information processing capability of CPU 5.

1. A navigation apparatus for guiding a vehicle along a driving route, comprising: a memory that stores 3D map data; and a controller that: sets a reference point on a route; sets a first point which is a first distance away from the reference point and a second point which is a second distance away from the reference point; sets a rectangular region along the route, the center line of the region passing through the first point and the second point, a side of the rectangular region closest to the first point being a predetermined distance beyond the first point in a travel direction of the vehicle; obtains 3D map data corresponding to the region; generates a 3D movie which has a predetermined viewpoint on the basis of the obtained 3D map data; and displays the generated 3D movie; wherein when the first point is set at an intersection, the controller sets a longer distance between the side of the region closest to the first point and the first point than a distance that would be set between the side of the region closest to the first point and the first point if the first point were not set at an intersection.
 2. The navigation apparatus according to claim 1, wherein the controller: determines whether any structures represented by the 3D map data are located within the region; and obtains the 3D map data representing the structures which were determined to be located within the region.
 3. The navigation apparatus according to claim 1, wherein: the route is made up of route data including nodes and links, each link connecting two adjacent nodes; and the first point and the second point are each set on one of the nodes.
 4. The navigation apparatus according to claim 1, wherein: the memory stores data corresponding to a plurality of the regions that are set along the searched route by the controller; and the controller: sets the destination; searches for the route to the destination; obtains data corresponding to at least one region among the plurality of regions stored in the memory in accordance with the motion of the current position; and obtains the 3D map data corresponding to the obtained region.
 5. The navigation apparatus according to claim 1, wherein: the controller sets at least two of the regions; and the at least two regions at least partially overlap.
 6. A navigation method for guiding a vehicle along a driving route, comprising: setting a reference point on a route; setting a first point which is a first distance away from the reference point and a second point which is a second distance away from the reference point; setting a rectangular region along the route, the center line of the region passing through the first point and the second point, a side of the rectangular region closest to the first point being a predetermined distance beyond the first point in a travel direction of the vehicle; obtaining 3D map data corresponding to the region; generating a 3D movie which has a predetermined viewpoint on the basis of the obtained 3D map data; displaying the generated 3D movie; and when the first point is set at an intersection, setting a longer distance between the side of the region closest to the first point and the first point than a distance that would be set between the side of the region closest to the first point and the first point if the first point were not set at an intersection.
 7. The navigation method according to claim 6, further comprising: determining whether any structures represented by the 3D map data are located within the region; and obtaining the 3D map data representing the structures which were determined to be located within the region.
 8. The navigation method according to claim 6, wherein: the route is made up of route data including nodes and links, each link connecting two adjacent nodes; and the first point and the second point are each set on one of the nodes.
 9. The navigation method according to claim 6, further comprising: storing data corresponding to a plurality of the regions that are set along the searched route by the controller; and setting the destination; searching for the route to the destination; obtaining data corresponding to at least one region among the plurality of regions stored in the memory in accordance with the motion of the current position; and obtaining the 3D map data corresponding to the obtained region.
 10. The navigation method according to claim 6, further comprising: setting at least two of the regions; wherein the at least two regions at least partially overlap.
 11. A non-transitory computer-readable storage medium storing a computer-executable program usable to guide a vehicle along a driving route, the program comprising: instructions for setting a reference point on a route; instructions for setting a first point which is a first distance away from the reference point and a second point which is a second distance away from the reference point; instructions for setting a rectangular region along the route, the center line of the region passing through the first point and the second point, a side of the rectangular region closest to the first point being a predetermined distance beyond the first point in a travel direction of the vehicle; instructions for obtaining 3D map data corresponding to the region; instructions for generating a 3D movie which has a predetermined viewpoint on the basis of the obtained 3D map data; instructions for displaying the generated 3D movie; and instructions for, when the first point is set at an intersection, setting a longer distance between the side of the region closest to the first point and the first point than a distance that would be set between the side of the region closest to the first point and the first point if the first point were not set at an intersection.
 12. The navigation apparatus according to claim 1, wherein: the set rectangular region is a first rectangular region; and the controller: sets a second rectangular region ahead of the first rectangular region in the travel direction; sets a third rectangular region ahead of the second rectangular region, the centerline of the third rectangular region being in a viewing direction from the second rectangular region; and gradually extends the center line from the first rectangular region, to the second rectangular region, and to the third rectangular region, as the vehicle travels.
 13. The navigation apparatus according to claim 12, wherein the controller: sets a fourth rectangular region that is after the second rectangular region in the travel direction and is after an intersection for which turning guidance will be given; and does not extend a centerline of the fourth rectangular region.
 14. The navigation method according to claim 6, wherein: the set rectangular region is a first rectangular region; and the method further comprises: setting a second rectangular region ahead of the first rectangular region in the travel direction; setting a third rectangular region ahead of the second rectangular region, the centerline of the third rectangular region being in a viewing direction from the second rectangular region; and gradually extending the center line from the first rectangular region, to the second rectangular region, and to the third rectangular region, as the vehicle travels.
 15. The navigation method according to claim 14, further comprising: setting a fourth rectangular region that is after the second rectangular region in the travel direction and is after an intersection for which turning guidance will be given; and not extending a centerline of the fourth rectangular region. 